1. Field of the Invention
The present invention relates to a device mounted on a pipeline pig for scraping paraffin from the inside of a pipeline. More particularly, this invention relates to a scraper element which is preferably made of polyurethane and which is provided with a cutting edge in the shape of parabola.
2. Prior Art
The use of pipeline pigs, and their construction, has been known in the petroleum industry. Generally speaking, a pipeline pig is an apparatus which is inserted into a pipeline and travels through the line, usually by the movement of liquids or gases in the line, to accomplish purposes such as cleaning the interior of the line, removing paraffin, separating one type of fluid from another, removing entrapped water, inspecting the pipeline and so forth.
Generally, pig apparatuses of the prior art include an elongated central body member (generally metallic) and two or more cup members (sections) which are attached to the body member. Each of the cup members is made of a resilient material, and completely fills the inside of the pipeline so that the pressure of the fluid being transported through the pipeline pushes the pig apparatus through the pipeline in the direction of fluid flow.
The pipeline industry uses pipeline pigs for many purposes. Some of the pigs carry brushes or scraping elements and are used to clean the inner walls of the pipeline. Others do not carry any cleaning elements and may be used as separation pigs to separate two different fluids being consecutively passed through the pipeline .
The present invention pertains to a cleaning pig and more particularly, to a cleaning pig which is adapted to remove paraffin from the inside surface of a pipeline. The cleaning pig of the present invention does not employ cleaning brushes, but, instead, a plurality of scraping elements or scraping blocks, as described herein, each of which is preferably made of polyurethane and which is provided with a parabolic cutting edge.
There are many patents and proposals in the past which have dealt with the problem of removing paraffin and other undesirable coatings from the inside of a pipeline. A preliminary search was conducted on the present invention and the following patents were uncovered in the search.
______________________________________ Patent No. Inventor Issued ______________________________________ 3,292,197 Stephens Dec. 20, 1966 3,480,984 Kidd Dec. 2, 1969 3,496,588 Ver Nooy Feb. 24, 1970 3,525,111 Von Arx Aug. 25, 1970 3,576,043 Zongker Apr. 17, 1971 3,604,041 Ver Nooy Sep. 14, 1971 3,673,629 Casey July 4, 1972 4,538,316 Reinhart Sep. 3, 1985 4,663,795 Neff May 12, 1987 5,379,475 Sivacoe Jan. 10, 1995 ______________________________________
Some scrapers involve brushes mounted at the end of leaf springs as in Stephens U.S. Pat. No. 3,292,197, or Ver Nooy U.S. Pat. No. 3,496,588. In Reinhart U.S. Pat. No. 4,538,316, a plurality of cutter arms are urged by springs against the pipeline wall.